Improvement in chemical telegraphy



UNITED STATES PATENT OEFIOE.

THOMAS A. EDISON, OF NEWARK, NEW JERSEY, ASSIGNOR To HIMSELE AND GEORGEHARRINGTON, OF WASHINGTON, D. O.

lMPROVEMENT IN CHEMICAL TELEGRAPHY.

Specification forming part of Letters Patent No. 166,861, dated August17, 1875; application filed July 25, 1874.

CASE No. 90.

To all whom it may concern:

Be it known that I, THOMAS A. EDISON, of Newark, in the county of Essexand State of New Jersey, have invented an Improvement in ChemicalTelegrephs, of which the following is a specification:

The object of this invention is to record dots and dashes uponchemically-prepared paper by electro-decomposition for telegraphicpurposes.

The invention consists in eombinin g a protosalt of iron with thesulpho-eyanide of potassium, in which the paper is to be moistened. Therecording-stylus is formed of platinum, or metal that is not oxidized bythe nascent oXygen.

The action is as follows: When the copper end of a galvanic battery isconnected to the platina stylus, resting on the paper that is moistenedin the abovesolution, and the zinc end is connected to the metal uponwhich it rests, oxygen is evolved at the platina point. This raises theprotoxide to a Sesquioxide or peroxide, when the sulpho-cyanide ofpotassium, which has no action on a protosalt of iron, combines with thehigher oxide to form the blood-red sulphocyanide of iron.

The reaction is very delicate. I prefer to use the protosalt of iron inthe form of the protosulphate of iron. Chloride of sodium added to thesolution increases the delicacy.

I claim as my invention- The combination of a protosalt'of iron,sulphO-cyanide of potassium, and a non-oxidizahle stylus, for thepurposes set forth.

Signed by me this 1st day of June, A. D.

THOS. A. EDISON.

Witnesses GEO. T. PINcKNEY, CHAS. H. SMITH.

